The guys at Build Explore Learn on youtube have put together the greatest AR build instructions of all time. They are easy to use and contain the distilled knowledge of decades of AR builds into video form. I have built a bunch of ARs and watched hours of videos, This is the best set of videos ever.

The AR-15 is the most common rifle in the U.S.A. It is a semi-automatic rifle modeled after the military’s automatic M16. The rifle is modular and can be customized with many different accessories. In this video, they discuss the full assembly of an AR-15 from individual parts.Below the video, there is a time index to put you in the section you need now, a list of required tools and a parts list.

1-1 Magazine Catch [01:30]
1-2 Bolt Catch [03:10]
1-3 Pivot Pin [05:27]
1-4 Safety Selector and Pistol Grip [07:12]
1-5 Trigger and Hammer [09:09]
1-6 Trigger Guard [14:14]
1-7 Buffer Tube and Take Down Pin [16:51]
1-8 Lubrication and Testing [22:24]
2-1 Ejection Port Cover [24:05]
2-2 Forward Assist [26:04]
2-3 Barrel, Gas Block, and Handguard [27:54]
2-4 Flash Suppressor [40:49]
2-5 Bolt Carrier Group [42:10]
2-6 Charging Handle [50:50]
2-7 Lubrication and Testing [52:40]
2-8 Headspace Check [55:35]
3 Live Fire Testing [01:01:57]
Here is a list of everything you need to build an AR-15 Tools: 1. Vise 2. AR-15 Lower Receiver Vise Block 3. Small Hammer 4. Set of Roll Pin Punches 5. Screwdriver 6. AR-15 Barrel Wrench 7. Set of Allen Wrenches (ie Hex Wrenches) 8. Gun Oil 9. Pivot Pin Installation Tool 10. Torque Wrench 11. Razor Blade 12. AR-15 Upper Receiver Vise Block 13. Snap Ring Pliers (Not covered in video. Only needed for certain types of handguards.) 14. 5.56 NATO / .223 Headspace Gauge 15. Clamp or Vise with rubber guards (for headspace checking) Optional Tools (not required, but they make the job easier): 16. Drill (if you desire to dimple barrel) 17. Blue Loctite 18. Dummy Cartridge 19. Brush and Rag for Cleaning 20. Needle Nose Pliers 21. Empty 5.56/.223 Shell Casing 22. Torque Screwdriver 23. Air Compressor 24. Pencil 25. Center Punch (if you desire to dimple castle nut) 26. Tape 27. Wood Block 28. Rubber Mallet
Parts: 1. Stripped Lower Receiver a. Purchase from Gun Store or FFL b. Depending on state laws, purchase from a private seller. c. Make your own. (Using a drill press, 3D printer, milling machine, etc.) 2. Lower Parts Kit a. Includes: Magazine Catch Button, Magazine Catch, Magazine Catch Spring, Bolt Catch, Bolt Catch Plunger, Bolt Catch Roll Pin, Bolt Catch Spring, Pivot Pin, Detent x 2, Detent Spring x2, Takedown Pin, Safety Selector, Selector Detent, Selector Spring, Trigger Guard, Roll Pin, Buffer Catch, Buffer Catch Spring b. Some LPKs do not include a trigger group i. Trigger, Trigger Spring, Hammer, Hammer Spring, Disconnector, Disconnector Spring, Hammer and Trigger Pins c. Some LPKs do not include a pistol grip i. Pistol Grip, Grip Screw 3. Trigger/Hammer Group (if not included in LPK) 4. Pistol Grip (if not included in LPK) 5. Buffer Tube Kit a. Buffer Tube i. If making an AR-15 Pistol, use a pistol tube instead. b. Nut c. Buffer Spring d. Receiver end plate e. Castle Nut f. Buffer i. Various Weights: H1, H2, or H3 6. Buttstock a. Illegal on an AR-15 Pistol (must use pistol tube) 7. Barrel and Barrel Nut 8. Handguard a. Sometimes includes a special barrel nut. 9. Gas Block Kit a. Gas Tube b. Gas Block c. Gas Tube Pin 10. Flash Hider/Muzzle Brake and Crush Washer 11. Stripped Upper Receiver 12. Ejection Port Cover Kit a. Ejection Port Cover b. Hinge Pin c. Hinge Pin Snap d. Hinge Spring 13. Forward Assist Kit a. Forward Assist (with pre installs Pawl) b. Forward Assist Retainer Pin c. Forward Assist Spring 14. Bolt Carrier Group a. Bolt i. Extractor Pin, Extractor with Spring, and Bolt b. Carrier i. Carrier, Cam Pin, and Retaining Pin c. Firing pin 15. Charging Handle a. with spring, latch, and roll pin if purchased separately. 16. Magazines a. Variety of sizes: 10, 20, 30, etc… 17. Sights/Optics.
Photo by Mark Miller